Well logging instruments that utilize radiation generators, such as sealed-tube neutron generators, have proven incredibly useful in formation evaluation. Such a neutron generator may include an ion source or ionizer and a target. An electric field, which is applied within the neutron tube, accelerates the ions generated by the ion source toward an appropriate target at a speed sufficient such that, when the ions are stopped by the target, fusion neutrons are generated and irradiate the formation into which the neutron generator is placed. The neutrons interact with elements in the formation, and those interactions can be detected and analyzed in order to determine characteristics of interest about the formation.
The generation of more neutrons for a given time period is desirable since it may allow an increase in the amount of information collected about the formation. Since the number of neutrons generated is related to, among others, the number of ions accelerated into the target, ion generators that generate additional ions are desirable. In addition, power can be a concern, so increases in ionization efficiency can be useful; this is desirable because power is often limited in well logging applications.
As such, further advances in the area of ion sources for neutron generators are of interest. It is desired for such ion sources to generate a larger number of ions than present ion sources for a given power consumption.